Research On Damage Identification Based On Reconstruction Algorithm For Probabilistic Inspection Of Damage For Composites

In recent years, composite materials are more and more widely applied in the structures such asaircraft because of their superior performance. But, it can hardly avoid occurring damages during theprocess of manufacturing and using the composites. Thus, the structural health monitoring system(SHMS) is needed to monitor the structure online. It is quite important and crucial for preventing thepotential safety hazard, which appears as a result of the degradation and failure of the structuralperformance, and reducing the maintenance cost by applying SHMS to evaluate the structural safetystatus and identify the structural damage in time.Structural health monitoring is such a research field with great extensive content. This thesismainly researches on the damage identification algorithm in this field. At first, reconstructionalgorithm for probabilistic inspection of damage (RAPID), which is a two step identification method,is proposed to firstly judge whether there is damage in the structure, and secondly identify thelocation and size of the damage. In this method, signal processing methods are applied to extract thefeatures of the Lamb wave signals. The difference coefficient, which is called as damage index (DI),is obtained by comparing the features of the reference and present signals. Then the probabilisticmethod is used to judge that the DI is caused by either the structural damage or the environmentalfactors and decide whether the damage occurs. And finally, the damage imaging algorithm is appliedto obtain a tomogram for damage identification. In order to verify the feasibility and effectiveness ofthis method, some structural damage identification experiments are carried out on composites. Theexperimental identification results are accurate and the image is clearness. In the end, a set of SHMSwith basic function is exploited based on the damage identification algorithm and virtual instrumenttechnology. And in addition, the system is verified to be effective through the experiments in thethesis.Both the damage identification algorithm researched and the SHMS exploited in this thesis canidentify the structural damages in composites accurately. It provides a feasible and effective methodfor using structural health monitoring in actual situation.